Mercury arc device



L. M. WITTLINGER .july 9,1946.

MERCURY ARC DEVICE Filed sept. 27, 1943 Patented July 9, l1.946

UNITED STATE MERCURY ARC DEVICE Leonard M. Wittlinger Flint Mich., or to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application september 27, 1943, semi No. 503,8'19

l This invention relates to lighting means and more specifically to means for producing ultraviolet rays.

'I'here are many instances in which ultraviolet rays are useful or necessary for various lighting problems and in .many of these sources of high voltage may not be readily obtainable. As an example of this, signaling or lighting under combat conditions make it necessary that no more than absolutely essential light be used for these purposes which might be discernible by an enemy. In moving vehicles at night under blackf out conditions, it has been found that by using some type of luminescent or uorescent paint, objects along a.4 path painted vtherewith can be discerned by projecting thereagainst ultraviolet rays to fluoresce the same' and indicate a course or path of the objects. In such vehicles. of course, the usual source of power is a storage battery or small generator having in the neighclaims. (on. 315-56) 2 specification and claims and the illustrations in the accompanying drawing, in which;

Figure 1 is a vertical section through a mercury y arc tube showing the'external circuit connections embodying one form of my invention.

Figures 2 and 3 are views similar to that of Figure 1, showing modified forms embodying my 'thereof an electrode 6 which is staked into a voltage to provide an arc section and therefore a source of ultraviolet rays.

However, in these instances the upper or`high potential electrode forming one end of the, arc gap is intended to be an anode and cooperate with .the mercury pool as cathode, but under certain I circumstances a reversal of polarity is obtained, making the upper electrode a cathode and causing it to erode or sputter and parts thereof to contact the inner surface of the surrounding tube and b'oth 'blanken the same and cause the electrode to wear away.

It is therefore an object of my invention to provide means for preventing sputtering or erodf ing of an electrode of a mercury arc device.

It is a further object of my invention to provide means to maintain the upper arc electrode at a positive potential with respect to the mercury electrode.

It is a still further object of vmy invention to small carbon disc 8 surrounded by a' ceramic disc ill. A second electrode i2 is supported in the side of the -envelope'and forms with the carbon electrode 8 the interrupter section of the tube. Slipported in the upperend of the tube 2 are two spaced electrodes i4 and il which project into the interior of the tube but are spaced from the upper surface of the mercury pool 4. The exterior electrical circuit includes a line I8 which connects electrode 6 with one side of a primary 20 of a transformer, the opposite side of the primary being connected through line 22 with a densers 3l and 3l' are connected in series across 4 between'these lines and. a center tap on the secondary 28 is connected through line 36 to ground inasmuch as the voltage is in suilicient to sus# .tain a mercury arc through vapor at this point.

The mercury therefore recondenses and the circuit is reformed to allow current to again ow. Thus an intermittent interruption of the current flowing through the primary coil 2li is obtained.

Therefore as the current in primary 20 is allowed to ow and is interrupted periodically, current will be induced in the secondary 28 in a ratio dependent upon 'the ratio of the turns of the coils and a relatively high voltage will be alternately applied first to electrode M and then to electrode l-B, dependent upon the direction of flow of cur' rent, but always oneor the other of these two electrodes will be at a ,positive potential with respect to the mercury4. 'I'hus there can be no reversal of polarity and the electrodes I4 and IB cannot become cathodes and the above identified defects will be cured.

Figure 2 shows another form of my invention in which the tube 2 is exactly the same as that shown in Figure 1 but the external circuit varies. The tube as before has two high potential electrodes It and I4 in the upper portion and the in terru-pter electrodes l 2 and 6, the latter being connected to the carbon disc 8 in contact with the mercury pool 4. In this casealso the lower electrode t is connected through line I8 with transformer primary T and thence through line 22 to the positive pole of the battery 24, the negative pole, as previously, being connected through line 26 to electrode I2. 'I'he transformer secondary 28 in this case, however, has one side connected through line 40 to rectifier electrode 42 of a double half wave rectiiler tube 44, the cooperating rectifier electrode 46 of which is connected through line 4B with tube electrode I6. In like manner the opposite side of the secondary 28' is connected through line 50 with a further rectifier electrode 52, the cooperating electrode 54 of which is connected through line 56 with the tube electrode I4. The center tap of the transformer is connected through line 58 with line 26, condenser 60 andcondenser 62. -Thus this form of my invention incorporates a positive rectifier between the output of the secondary of vthe .transformer andthe two high tension electrodes I4 and I6. The operation is the same generally as in the previous instance, the electrodes I4 and I6 alternately becoming the positive electrode with respect to the mercury meniscus to provide the arc.

' In ,Figure 3 there is shown a different style of 1 tube and in this instance the tube envelope 2 has a pool of mercury 4' therein and the lower or base portion of the tube supports an electrode I2 in spaced relation to a second electrode 6. This latter electrode 6' is staked into a vertical carbon electrode 64 which in this instance is sealed by an insulating sleeve 66 leaving only an angular upper surface 68 exposed to the mercury.

This provides the interrupter section of the tube. The upper portion of the tube is evacuated and the upper end supports an arc electrode 10. The electrode 6 is connected by line 12 to the positive pole of the battery u. the negative pole of which 1 is connected through line 14 with-one terminal of the primary transformer winding 20", the other terminal of which is connected by line 16 to tube electrode l2'. The secondary winding 28" Ahas one terminal connected through line 18 to condenser 80, the opposite side of which is connected directly by the line 82 with one electrode 84 of a rectiiler'tube B6. The other rectifier electrode 88 is connected through line 9i! with the other side of the secondary 28". A condenser 92 is connected directly across the secondary 28" and line 1l is connected to a line 94 whichextends to line 12 connected to the positive lpole of the battery. Line 82 is alsoconnected to conductive line 96 which extends to the arc electrode 10. In this instance, as in the previous case, the interruptor electrodes 6', 64, 4 and I2' provide a periodic pulsating current'in the primary 20' of the transformer. This induces a similar current of higher voltage in the secondary 28" which current is rectified by the tube 86 and applied to the electrode 1l to maintain the same always positive materials ymounted in the casing and contacting.

the mercury, a low voltage source of power connected to said electrodes to form therewith an interrupter, a transformer in the low voltage circuit, a high voltage circuit connected to the transformer, further electrode means mounted inl the casing spaced from'the mercury and connected tothe high voltage circuit to cause an arc to form between the last-named electrode means and the' mercury and means in the high voltage circuit to maintain a given arc polarity of the -mercury and last-named electrode means.

2. In a light source for ultraviolet rays, a transparent casing, a pool of mercury partially filling said casing, a plurality of electrodes of dissimilar materials mounted in the casing and contacting the mercury, a low voltage source of power connected to said electrodes to form therewith an mterrupter, a transformer in the low voltage circuit, a high voltage circuit connected to the transformer, further arc electrode means mounted in the casing spaced from the mercury and connected to the high voltage circuit to cause an arc to form between the last-named electrode means and the mercury, and .rectifier means in the high voltage circuit to maintain the arc electrode means at a positive potential with respect to the mercury pool.

3. In a light source for ultraviolet rays, a tube partially filled with mercury having an interrupter section and an arc section, a low voltage source of power connected to the interrupter section, a transformer having a high and low potential winding, the latter being connected into the low voltage circuit, a high voltage circuit lconnecting the high voltage winding with the arc section and means to maintain the arc section of constant polarity during its operation.

4. In a light source for ultraviolet rays, a tube partially lled ,with mercury, a plurality of electrodes carried by the tube, some of which are immersed in the mercury and some spaced therefrom, low voltage means connected to the immersed electrodes and forming there/with an interrupter, and means for alternately applying a higher potential than that of the mercury to the spaced electrodes to draw an arc from the mercury` meniscus maintaining the latter as a cathode.

5. In a light source for ultraviolet rays, a tu-be partially filled with mercury, a plurality of elec- 6. In a light source for ultraviolet rays. a tube partially filled with mercury, a plurality of electrodes carried by the-tube, some of which are immersedA in the mercury and some spaced therefrom, low voltage means connected to the immersed electrodes and forming therewith an interrupter, transformer means having primary and secondary circuits, the primary being connecte'd to the low voltage circuit and the sec-`v ondary to the spaced electrodes to voltage thereto to create an arc be ween theml partially filled with mercury, 'a plurality of elec- I trode's carried by the tube, some of which are pply high' 6 means and means in said secondary circuit to maintain the polarity of said conductive means p the same at all times during energization.

9. In a light source, a transparent casing, a

5 pool of electrically conductive fluid in said casing, electrode means mounted in the casing spaced from the surface of the iiuid, a primary circuit having fluctuating current owing therein, a secondary circuit coupled thereto and interconimmersed in the'mercury and some spaced there- 10 necting said electrode means and the fluid to from, low'voltage means connected tothe immersed electrodes and forming therewith an interrupter, 'transformer means comprising primary. and secondary windings, the primary being connected `to the low voltage circuit and the secondary to the spaced electrodes to apply high voltage thereto to create an arc between them and the mercury meniscus, and means for grounding the center Vof the transformer secondary. f

8. In a light source, a casing, conductive means between which an arc may be created supported necting said primary circuit; and said conductive cause an arc to form therebetween and means in the secondary circuit to maintain the electrode means at the same polarity with respect to the fluid at al1 times during operation.

10. In a light source. a transparent casing, a

pool oi?v mercury partially lling said casing, electrode means mounted in said casing spaced'from the surface of the mercury, a primary circuit having uctuating current flowing therein, a sec- 20 ondary circuit coupled thereto and interconnecting said electrode means and said mercury to cause an arc to form therebetween and ,means in the secondary circuit to maintain the electrode means at a positive potential with respect'to the 25 mercury at all times. Y

.LEONARD M. WITTLINGER. I 

